Add Pause and Resume to Web TTS & Extension TTS APIs

The web speech spec already includes pause and resume, this
completes the implementation. For parity, this change also adds
support for Pause and Resume to Chrome's TTS extension API
and TTS Engine extension APIs.

BUG=171887

Review URL: https://chromiumcodereview.appspot.com/15108002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@203146 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

linux/system.gyp

@@ -517,6 +517,8 @@
                      'spd_say',
                      'spd_stop',
                      'spd_close',
+                     'spd_pause',
+                     'spd_resume',
                      'spd_set_notification_on',
                      'spd_set_voice_rate',
                      'spd_set_voice_pitch',